Spider venoms contain hundreds of components, including neurotoxic peptides and proteins. These venom components are of interest for their potential use as therapeutic drugs and as tools for neurophysiology research, as many of them specifically inhibit or activate ion channels and receptors in nerve cells. In addition, some venom peptides are species-specific. For example, certain peptides only affect insects but are harmless to mammals; consequently, it is possible that spider venom peptides could be used as environmentally-friendly insecticidal toxins. The aim of this research is to discover interesting peptides and proteins from the venom of the brown recluse spider and its relatives (the Sicariidae spiders), and then to characterize the structure and function of these peptides and proteins. In Specific Aim 1, the diversity of venom components from Sicariidae spiders will be explored by chromatographic separation of crude venom as well as by the analysis of cDNA libraries created from venom gland mRNA. This will help in understanding the patterns of molecular evolution of these toxins and identify peptides for further study. In Specific Aim 2, interesting peptides will be expressed in bacteria using recombinant DNA techniques to generate samples for further structural and functional characterization. Structural characterization will be carried out using NMR (nuclear magnetic resonance) spectroscopy. Finally, in Specific Aim 3, the toxicity and method of action of these peptides will be characterized. By identifying and then expressing venom peptides and proteins the proposed research aims to characterize the structure and function of these venom components with the goals of discovery of novelty and analyses of structural evolution. PUBLIC HEALTH RELEVANCE: The proposed research aims to identify neurotoxic peptides and proteins from spider venoms and then to determine their structure and function. Spider venom peptides and proteins are of interest for their potential use as therapeutic drugs and as tools for neurophysiology research, as many of them are believed to specifically inhibit or activate ion channels and receptors in nerve cells. In addition, some venom peptides are species-specific and therefore have the potential to be used as environmentally friendly insecticidal toxins. [unreadable] [unreadable] [unreadable] [unreadable]